1. Field of the Invention
The present invention relates to sports such as racquet sports and more particularly to training devices for helping players analyze their swing using centripetal force generated during the swing to generate an audible or visible signal that is fed back to the player when a desired velocity threshold is reached or exceeded.
There are a number of different sports which use hand held implements such as racquets, baseball bats, cricket bats, golf clubs and the like, to hit an object, typically a round ball. Tennis is perhaps the most popular of all racquet sports, however, arguably the most difficult to master. The proper stroking of a racquet to hit or serve a tennis ball requires not only a proper position of the racquet, but also a swing of sufficient and well timed force, such that the moment of greatest force occur at impact, rather than before or after impact.
2. General Background
A number of devices have been patented which have attempted to solve the problem of indicating in some way to the user of a racquet or other hand held sport implement, the speed of the swing. These prior patented devices have attempted to indicate speed, sometimes through a signal so that the user can improve his or her swing and thus hopefully improve his or her game. An example of a recent patent entitled "Swing Speed Analyzer" is U.S. Pat. No. 4,377,125 issued to Leonard Westfall. The Westfall patent provides a training or practice device especially designed for use on an athletic club type equipment such as a golf club, tennis racquet, baseball bat or the like which is swung to strike a game ball during normal game ball use and which device is releasably attached to the club, racquet, or bat and operable to provide an audible and visual indication when the swing of the club type equipment has the optimum velocity and power for striking the game ball. The device is manually resetable after each swing of the equipment, for subsequent and repeatable use whereby the user by practice may repeatedly obtain the optimum velocity and power of each swing of the equipment. The device uses a sliding plunger held in an initial position by a transversely positioned screw that presses against a snap. The device produces an audible "click" when two surfaces come quickly together during the swing. A tuning fork can provide for amplification of the sound of impact of the two striking surfaces.
U.S. Pat. No. 4,094,504 issued to Kenneth Barasch entitled "Signalling Device To Be Used With A Sport Implement For Detecting And Indicating The Proper Or Improper Use Thereof" relates to a signalling device which can be connected to a sport implement so as to audibly indicate the fact that the user is or is not using the implement in the properly intended manner. The device includes an air actuable signalling device that includes a plurality of reeds, each of the reeds having a longitudinal axis, for emitting an audible signal when air passes through the device in a predetermined manner. Some of the reeds are mounted on the tennis racquet in a first direction so as to indicate a proper forehand stroke of the tennis racquet and the other ones of the reed members are mounted on the tennis racquet in a direction opposite from the first direction so as to indicate a proper backhand stroke of the tennis racquet.
Another tennis training device that produces an audible signal is disclosed in the Conrey U.S. Pat. No. 4,101,132 entitled "Electronic Athletic Equipment." The Conrey device provides a tennis racquet or any other similar athletic instrument for striking a movable ball or other playing element and includes electronic sensors for providing an audible or audio visual indication of the location on the racquet or instrument at which contact is made with the ball or other playing element. Various devices for sensing the location of the contact are disclosed.
A golf swing practice club is the subject of U.S. Pat. No. 3,575,419 issued to Wallace E. Davis. The Davis patent provides a golf swing practice club with a linear shaft having a handle at one end and a weighed body at the other end. The body provides an axial bore with a spring biased plunger slidably mounted therein. The plunger has an annular groove therein for removably receiving a spring-biased ball detent for yieldingly holding the plunger in its initial or starting position. An anvil screw closes the outer end of the axial bore and a swinging of the club at a certain speed in a golf swing will cause the plunger to move along the bore by centrifugal force and to strike the anvil screw with a loud click. The follow through portion of the golf swing will slow the speed of the club and permit the plunger spring to reset the plunger with a less loud click and the ball detent will yieldingly hold the plunger in its reset position ready for the next golf swing.
U.S. Pat. No. 1,136,546 issued to Joseph Connelly discloses a swingable practice game implement with a sliding weight. A shaft has a head in which the sliding weight is mounted for limited axial movement. A spring pressed ball detent is carried by the weight and received in short keeper grooves for spacing the weight a predetermined distance from a stop collar and another set of spring pressed ball detents are carried by the weight and are receivable in a second keeper groove for spacing the weight a less distance from the stop collar. The weight has a projection that extends through an opening in the stop collar and this projection is manually depressed after each swing of the device by the user to reset the sliding weight.
An early patent No. issued to A. M. Maroth, U.S. Pat. No. 2,780,098, is entitled "Indicating Cage Responsive To Circular Or Angular Velocity." The Maroth U.S. Pat. No. 2,780,098 provides an indicating gauge responsive to velocity along an arcuate path and includes a guide that is adapted to be radially disposed with respect to the arcuate path. In response to swinging of the racquet, bat, golf club, or the like, an indicating member is driven against the force of a return spring. The indicating member cooperates with a calibrated scale to indicate the circular or angular velocity of the swing or the speed or probable distance traveled by a struck ball or other object and the indicating member is retained in the position thereof corresponding to the maximum displacement of the mass during the swing until the indicating member is released for return to its original zero indicating position.
Several other patents are directed generally to the problem of signaling the user of a tennis racquet including, for example, the Bates U.S. Pat. No. 4,063,730 entitled "Tennis Racquet Swing Training Device," and the Richards U.S. Pat. No. 4,535,986 entitled "Inclination Signalling Device On A Tennis Racquet."
These devices as above-described suffer in that they do not provide an indicator of a desired threshold velocity value so that a player knows when peak force occurs and thereby know if peak force occurred at contact which is desirable and indicates good timing. It is important in developing proper tennis form that peak force of the swing coincide with ball contact. Thus, the present invention solves this prior art problem by providing an audible signal at peak force of the swing and allows the performer to practice placing peak force at the moment of contact.